'Freud's Last Session' is one for the ageless

"Freud's Last Session" is no "King Lear." And there is nothing in the air to suggest that Mike Nussbaum is slowing down his busy slate of theatrical engagements. Perish the very thought.

Still, the role of a dying Sigmund Freud in Mark St. Germain's thoughtful, well-constructed and lucid two-character drama is a formidable undertaking for any actor, let alone one who happens to be 88 years old (Freud, at the late-in-life moment Nussbaum plays him here, was a considerably younger man at 83). And for those of us who've seen a chunk of Nussbaum's 50-year-career on the stage, much of it in this town, this is a remarkable milestone by a peerless Chicago actor.

With the decent original cast headed back to the simultaneous commercial production in New York, Nussbaum now has taken over the role of Freud, while Coburn Goss now plays C.S. Lewis, in an accessible, commercially produced play at the Mercury Theater that imagines these two intellectual giants meeting in London on the eve of the Second World War, all fired up to talk about God, sex, science, faith, death and Jesus, with neither one winning out in a scrupulously balanced drama designed mostly to get audience members thinking and talking.

There are a very select few performers who can still hold down demanding stage roles as they approach their 90th year, maybe even in a talky, two-person show, but Nussbaum doesn't hold anything down in that sense. The father of psychotherapy is no grandfatherly cameo. Nussbaum's performance as Freud is a typically shrewd concoction of sardonic humor, savvy riposte, intellectual banter and, most crucially of all, a deeply poignant sense of personal mortality. It is a performance full of grief and optimism.

In the play, Freud's mouth and jaw are afflicted with cancer, and the failings of his character's body seem to underpin all that Nussbaum does here, even though it undermines none of his spirit or resilience.

Nussbaum's work on stage long has been characterized by a furious discipline — as is typical but also incredible, he has no palpable memorization issues whatsoever in this huge role — combined with his unique mix of big-hearted vulnerability, deadpan timing and ceaseless determination.

When playing a man of this age, it helps when the actor already has exceeded it, enabling him to look back on his character with the truth of experience, rather than having to come up with those artificially theatrical cues of age that never replicate the life experience of the actually old.

Nussbaum does none of that crude stuff. There are no greasepaint lines on his face. His Freud is sprightly and smart but intensely irritated that his own body is failing him. And that's exactly, it feels, like what the man himself would have been in this difficult moment. Nussbaum understands that the key to this part is not about acting old and sick. It is about shaking all that off at every possible moment and carrying on. And at this point in his own life, he is free so to do.

Goss, who makes an erudite and appealing Lewis, is also able to reveal that great writer's somewhat smug side, as well as the way his faith is both unshakable and up for grabs. This is, after all, a young man as yet unaware of many of life's mysteries.

It's a fine performance from this Chicago actor, shot through with honesty, although you wish he'd go after Nussbaum's Freud with yet more venom when his facade slips. Nussbaum would give back all he gets. It is hard for atheists and Christians to compromise.

Still, "Freud's Last Session" is now quite a moving night at the theater as well as a source of some well-paced food for the mind.

Alas, it is easy for Chicago to take Nussbaum for granted; he has been around so very long and makes it all look so easy. But it's worth saying — nay, shouting — that he now does what almost no one else in his profession can do. His familiarity should not diminish his extraordinary ongoing achievement, eight times a week on Southport Avenue.